This study develops a nonlinear full vehicle dynamic model (VNDM) of a mining dump truck to evaluate the ride comfort performance of the driver’s seat equipped with an air suspension (AS), compared with the same seat using a conventional spring suspension (SS), under representative operating conditions. Two driver seat suspension dynamic models are formulated to compute vertical suspension forces and are then coupled with the VNDM. Ride comfort effectiveness is quantified by two objective metrics: (i) the root mean square (RMS) and power spectral density (PSD) of the vertical acceleration of the driver’s seat, evaluated in accordance with ISO 2631-1:1997, and (ii) the cab pitch and roll angular accelerations. The evaluation shows that, compared with conventional SS, AS yields significantly lower values for both metrics, leading to a marked improvement in driver seat comfort on an ISO class-D road surface at 35 km/h under full load. These findings provide a basis for the design and tuning of seat suspension systems for off-road vehicles.